Cytosinium orotate dihydrate.

The title compound, C4H6N3O(+)·C5H3N2O4(-)·2H2O or Cyt(+)·Or(-)·2H2O, was synthesized by a reaction between cytosine (4-amino-2-hy-droxy-pyrimidine, Cyt) and orotic acid (2,4-dihy-droxy-6-carb-oxy-pyrimidine, Or) in aqueous solution. The two ions are joined by two N(+)-H⋯O(-) (±)-(CAHB) hydrogen bonds, forming a dimer with graph-set motif R2(2)(8). In the crystal, the ion pairs of the asymmetric unit are joined by four N-H⋯O inter-actions to adjacent dimers, forming hydrogen-bonded rings with R2(2)(8) graph-set motif in a two-dimensional network. The formation of the three-dimensional array is facilitated by water mol-ecules, which act as bridges between structural sub-units linked in R3(2)(8) and R3(2)(7) hydrogen-bonded rings. The orotate anion is essentially planar, as the dihedral angle between the planes defined by the carboxylate group and the uracil fragment is 4.0 (4)°.

Related literature

For the supra­molecular association in proton-transfer adducts containing mol­ecules of biological inter­est, see: Portalone & Colapietro (2007 ▶, 2009 ▶); Portalone (2010 ▶, 2011 ▶); Portalone & Irrera (2011 ▶). For the crystal structure of neutral cytosine, see: McClure & Craven (1973 ▶). For the crystal structures of orotic acid and its salts, see: Lutz (2001 ▶); Portalone (2008 ▶); Solbakk (1971 ▶). For computation of ring patterns formed by hydrogen bonds in crystal structures, see: Bernstein et al. (1995 ▶).

Experimental

Crystal data

C4H6N3O+·C5H3N2O4 −·2H2O

M = 303.24

Monoclinic,

a = 5.1486 (2) Å

b = 15.1631 (6) Å

c = 16.4206 (7) Å

β = 90.562 (3)°

V = 1281.87 (9) Å3

Z = 4

Mo Kα radiation

μ = 0.14 mm−1

T = 298 K

0.15 × 0.10 × 0.10 mm

Data collection

Oxford Diffraction Xcalibur S CCD diffractometer

Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2006 ▶) T min = 0.980, T max = 0.987

27833 measured reflections

2328 independent reflections

1954 reflections with I > 2σ(I)

R int = 0.034

Refinement

R[F 2 > 2σ(F 2)] = 0.046

wR(F 2) = 0.125

S = 1.13

2328 reflections

228 parameters

4 restraints

H atoms treated by a mixture of independent and constrained refinement

Δρmax = 0.20 e Å−3

Δρmin = −0.21 e Å−3

Data collection: CrysAlis CCD (Oxford Diffraction, 2006 ▶); cell refinement: CrysAlis RED (Oxford Diffraction, 2006 ▶); data reduction: CrysAlis RED; program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: WinGX (Farrugia, 2012 ▶); software used to prepare material for publication: WinGX (Farrugia, 2012 ▶).

Click here for additional data file.

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812049057/rz5024sup1.cif

Click here for additional data file.

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812049057/rz5024Isup2.hkl

Click here for additional data file.

Supplementary material file. DOI: 10.1107/S1600536812049057/rz5024Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

C4H6N3O+·C5H3N2O4−·2H2O	F(000) = 632
Mr = 303.24	Dx = 1.571 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2ybc	Cell parameters from 14285 reflections
a = 5.1486 (2) Å	θ = 2.7–29.0°
b = 15.1631 (6) Å	µ = 0.14 mm−1
c = 16.4206 (7) Å	T = 298 K
β = 90.562 (3)°	Tablets, colourless
V = 1281.87 (9) Å3	0.15 × 0.10 × 0.10 mm
Z = 4

Oxford Diffraction Xcalibur S CCD diffractometer	2328 independent reflections
Radiation source: Enhance (Mo) X-ray source	1954 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.034
Detector resolution: 16.0696 pixels mm-1	θmax = 25.3°, θmin = 2.7°
ω and φ scans	h = −6→6
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2006)	k = −18→18
Tmin = 0.980, Tmax = 0.987	l = −19→19
27833 measured reflections

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.046	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.125	H atoms treated by a mixture of independent and constrained refinement
S = 1.13	w = 1/[σ2(Fo2) + (0.0662P)2 + 0.3271P] where P = (Fo2 + 2Fc2)/3
2328 reflections	(Δ/σ)max < 0.001
228 parameters	Δρmax = 0.20 e Å−3
4 restraints	Δρmin = −0.21 e Å−3

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > 2σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

	x	y	z	Uiso*/Ueq
O5	0.2952 (3)	0.32438 (9)	0.16089 (11)	0.0590 (5)
N7	0.6235 (3)	0.26032 (12)	0.09082 (11)	0.0419 (5)
H7	0.678 (5)	0.3059 (15)	0.0814 (14)	0.046 (6)*
C8	0.4062 (4)	0.25827 (12)	0.13766 (12)	0.0382 (5)
N10	0.3426 (4)	0.02351 (12)	0.15490 (11)	0.0453 (5)
H10A	0.193 (5)	0.0195 (17)	0.1906 (16)	0.067 (7)*
H10B	0.427 (4)	−0.0231 (16)	0.1400 (13)	0.051 (6)*
N9	0.3208 (3)	0.17444 (10)	0.15622 (10)	0.0349 (4)
H9	0.188 (5)	0.1701 (14)	0.1872 (16)	0.055 (7)*
C10	0.4331 (3)	0.09908 (11)	0.13046 (11)	0.0331 (4)
C11	0.6503 (4)	0.10687 (13)	0.07734 (12)	0.0391 (5)
H11	0.7293	0.0571	0.0555	0.050 (6)*
C12	0.7361 (4)	0.18745 (13)	0.06001 (12)	0.0398 (5)
H12	0.8776	0.1937	0.0257	0.048 (6)*
O1	−0.7741 (2)	−0.06618 (8)	0.44582 (8)	0.0403 (4)
O2	−0.8140 (3)	0.23043 (8)	0.45689 (9)	0.0485 (4)
O3	−0.0719 (3)	0.01695 (8)	0.27044 (9)	0.0474 (4)
O4	−0.0853 (3)	0.16324 (8)	0.26139 (8)	0.0440 (4)
N1	−0.4837 (3)	0.01212 (10)	0.36986 (9)	0.0322 (4)
H1	−0.419 (4)	−0.0379 (14)	0.3528 (11)	0.039 (5)*
C2	−0.6871 (3)	0.00513 (11)	0.42196 (10)	0.0293 (4)
N3	−0.7902 (3)	0.08258 (9)	0.44828 (9)	0.0318 (4)
H3	−0.932 (4)	0.0768 (13)	0.4826 (13)	0.042 (5)*
C4	−0.7074 (4)	0.16627 (11)	0.42733 (11)	0.0323 (4)
C5	−0.4941 (4)	0.16797 (11)	0.37152 (11)	0.0325 (4)
H5	−0.4283	0.2217	0.3539	0.039*
C6	−0.3900 (3)	0.09262 (11)	0.34486 (10)	0.0289 (4)
C7	−0.1609 (3)	0.09014 (11)	0.28677 (10)	0.0307 (4)
O6W	0.7353 (4)	−0.09802 (12)	0.10206 (16)	0.0836 (7)
H61	0.733 (8)	−0.1472 (17)	0.078 (2)	0.125*
H62	0.812 (8)	−0.112 (3)	0.1479 (16)	0.125*
O7W	−0.1266 (4)	0.35051 (13)	0.28142 (14)	0.0868 (7)
H71	−0.125 (8)	0.2911 (13)	0.278 (2)	0.130*
H72	−0.033 (7)	0.373 (2)	0.2403 (18)	0.130*

	U11	U22	U33	U12	U13	U23
O5	0.0601 (10)	0.0344 (8)	0.0831 (12)	0.0029 (6)	0.0346 (9)	0.0003 (7)
N7	0.0389 (10)	0.0309 (9)	0.0561 (11)	−0.0062 (7)	0.0192 (8)	0.0093 (8)
C8	0.0359 (11)	0.0339 (10)	0.0448 (11)	−0.0012 (8)	0.0129 (8)	0.0059 (8)
N10	0.0468 (11)	0.0310 (9)	0.0585 (11)	−0.0032 (8)	0.0238 (9)	0.0019 (8)
N9	0.0295 (9)	0.0344 (9)	0.0411 (9)	−0.0020 (6)	0.0149 (7)	0.0045 (6)
C10	0.0297 (10)	0.0338 (9)	0.0359 (10)	−0.0031 (7)	0.0069 (8)	0.0020 (7)
C11	0.0368 (11)	0.0377 (10)	0.0431 (11)	0.0007 (8)	0.0161 (8)	0.0020 (8)
C12	0.0323 (11)	0.0445 (11)	0.0431 (11)	−0.0010 (8)	0.0167 (8)	0.0082 (9)
O1	0.0435 (8)	0.0247 (6)	0.0534 (8)	0.0003 (5)	0.0287 (6)	0.0030 (6)
O2	0.0573 (9)	0.0240 (6)	0.0648 (9)	0.0027 (6)	0.0322 (7)	−0.0025 (6)
O3	0.0467 (9)	0.0344 (7)	0.0616 (9)	0.0021 (6)	0.0304 (7)	0.0024 (6)
O4	0.0451 (8)	0.0338 (7)	0.0536 (8)	−0.0068 (6)	0.0281 (7)	0.0031 (6)
N1	0.0325 (9)	0.0256 (8)	0.0388 (9)	0.0000 (6)	0.0175 (7)	−0.0004 (6)
C2	0.0282 (10)	0.0266 (9)	0.0332 (9)	−0.0003 (7)	0.0130 (7)	0.0020 (7)
N3	0.0306 (8)	0.0274 (8)	0.0376 (8)	0.0002 (6)	0.0184 (7)	0.0009 (6)
C4	0.0343 (10)	0.0246 (8)	0.0383 (10)	−0.0016 (7)	0.0118 (8)	0.0018 (7)
C5	0.0339 (10)	0.0253 (8)	0.0385 (10)	−0.0040 (7)	0.0134 (8)	0.0028 (7)
C6	0.0260 (9)	0.0312 (9)	0.0297 (9)	−0.0043 (7)	0.0067 (7)	0.0044 (7)
C7	0.0268 (9)	0.0320 (9)	0.0334 (9)	−0.0030 (7)	0.0095 (7)	0.0014 (7)
O6W	0.0904 (15)	0.0403 (9)	0.1201 (19)	0.0107 (9)	0.0027 (13)	−0.0186 (11)
O7W	0.0985 (15)	0.0480 (10)	0.1149 (17)	−0.0042 (10)	0.0569 (13)	−0.0065 (11)

O5—C8	1.217 (2)	O3—C7	1.231 (2)
N7—C12	1.349 (2)	O4—C7	1.248 (2)
N7—C8	1.364 (2)	N1—C2	1.363 (2)
N7—H7	0.76 (2)	N1—C6	1.377 (2)
C8—N9	1.380 (2)	N1—H1	0.88 (2)
N10—C10	1.302 (2)	C2—N3	1.361 (2)
N10—H10A	0.97 (3)	N3—C4	1.383 (2)
N10—H10B	0.87 (2)	N3—H3	0.93 (2)
N9—C10	1.351 (2)	C4—C5	1.437 (2)
N9—H9	0.86 (3)	C5—C6	1.338 (2)
C10—C11	1.430 (2)	C5—H5	0.9300
C11—C12	1.331 (3)	C6—C7	1.525 (2)
C11—H11	0.9300	O6W—H61	0.845 (19)
C12—H12	0.9300	O6W—H62	0.871 (19)
O1—C2	1.2357 (19)	O7W—H71	0.902 (19)
O2—C4	1.220 (2)	O7W—H72	0.898 (19)
C12—N7—C8	123.41 (17)	C2—N1—H1	115.5 (13)
C12—N7—H7	120.5 (18)	C6—N1—H1	122.5 (13)
C8—N7—H7	116.1 (18)	O1—C2—N3	120.71 (14)
O5—C8—N7	123.23 (17)	O1—C2—N1	123.39 (15)
O5—C8—N9	122.53 (16)	N3—C2—N1	115.89 (14)
N7—C8—N9	114.23 (16)	C2—N3—C4	126.19 (14)
C10—N10—H10A	121.9 (15)	C2—N3—H3	114.9 (12)
C10—N10—H10B	116.6 (15)	C4—N3—H3	118.9 (12)
H10A—N10—H10B	121 (2)	O2—C4—N3	119.45 (15)
C10—N9—C8	124.86 (15)	O2—C4—C5	126.07 (15)
C10—N9—H9	117.9 (15)	N3—C4—C5	114.48 (14)
C8—N9—H9	117.3 (15)	C6—C5—C4	120.29 (15)
N10—C10—N9	119.49 (16)	C6—C5—H5	119.9
N10—C10—C11	123.05 (17)	C4—C5—H5	119.9
N9—C10—C11	117.46 (15)	C5—C6—N1	121.14 (15)
C12—C11—C10	117.99 (17)	C5—C6—C7	122.74 (15)
C12—C11—H11	121.0	N1—C6—C7	116.11 (15)
C10—C11—H11	121.0	O3—C7—O4	127.60 (15)
C11—C12—N7	121.83 (16)	O3—C7—C6	116.76 (15)
C11—C12—H12	119.1	O4—C7—C6	115.65 (15)
N7—C12—H12	119.1	H61—O6W—H62	102 (3)
C2—N1—C6	121.99 (15)	H71—O7W—H72	109 (3)
C12—N7—C8—O5	−175.0 (2)	N1—C2—N3—C4	−0.2 (3)
C12—N7—C8—N9	4.6 (3)	C2—N3—C4—O2	−178.38 (18)
O5—C8—N9—C10	178.4 (2)	C2—N3—C4—C5	0.9 (3)
N7—C8—N9—C10	−1.2 (3)	O2—C4—C5—C6	178.4 (2)
C8—N9—C10—N10	176.86 (19)	N3—C4—C5—C6	−0.8 (3)
C8—N9—C10—C11	−2.7 (3)	C4—C5—C6—N1	0.1 (3)
N10—C10—C11—C12	−176.2 (2)	C4—C5—C6—C7	−178.95 (16)
N9—C10—C11—C12	3.4 (3)	C2—N1—C6—C5	0.7 (3)
C10—C11—C12—N7	−0.2 (3)	C2—N1—C6—C7	179.75 (16)
C8—N7—C12—C11	−4.0 (3)	C5—C6—C7—O3	175.70 (18)
C6—N1—C2—O1	−179.52 (17)	N1—C6—C7—O3	−3.4 (2)
C6—N1—C2—N3	−0.6 (3)	C5—C6—C7—O4	−4.2 (3)
O1—C2—N3—C4	178.74 (18)	N1—C6—C7—O4	176.72 (16)

D—H···A	D—H	H···A	D···A	D—H···A
N7—H7···O1i	0.76 (2)	2.05 (2)	2.809 (2)	172 (2)
N10—H10A···O3	0.97 (3)	1.90 (3)	2.871 (2)	173 (2)
N10—H10B···O6W	0.87 (2)	2.05 (2)	2.876 (3)	158 (2)
N9—H9···O4	0.86 (3)	1.87 (3)	2.7299 (19)	176 (2)
N1—H1···O5ii	0.88 (2)	2.20 (2)	3.051 (2)	165.6 (17)
N3—H3···O1iii	0.93 (2)	1.93 (2)	2.8624 (18)	179.3 (19)
O6W—H61···O2ii	0.85 (2)	1.99 (2)	2.806 (2)	163 (4)
O6W—H62···O7Wiv	0.87 (2)	2.07 (3)	2.873 (4)	154 (4)
O7W—H71···O4	0.90 (2)	1.97 (2)	2.867 (2)	173 (4)
O7W—H72···O5	0.90 (2)	2.27 (3)	2.979 (2)	136 (3)

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N7—H7⋯O1i	0.76 (2)	2.05 (2)	2.809 (2)	172 (2)
N10—H10A⋯O3	0.97 (3)	1.90 (3)	2.871 (2)	173 (2)
N10—H10B⋯O6W	0.87 (2)	2.05 (2)	2.876 (3)	158 (2)
N9—H9⋯O4	0.86 (3)	1.87 (3)	2.7299 (19)	176 (2)
N1—H1⋯O5ii	0.88 (2)	2.20 (2)	3.051 (2)	165.6 (17)
N3—H3⋯O1iii	0.93 (2)	1.93 (2)	2.8624 (18)	179.3 (19)
O6W—H61⋯O2ii	0.85 (2)	1.99 (2)	2.806 (2)	163 (4)
O6W—H62⋯O7W iv	0.87 (2)	2.07 (3)	2.873 (4)	154 (4)
O7W—H71⋯O4	0.90 (2)	1.97 (2)	2.867 (2)	173 (4)
O7W—H72⋯O5	0.90 (2)	2.27 (3)	2.979 (2)	136 (3)

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) .